When using discrete light sources, such as light emitting diodes, to create an illumination effect, there is a need for blending the illumination created by these discrete light sources into a uniform lighting condition. For example, a linear array of discrete light sources will produce non-uniform emission which can be very detrimental for sterilization purposes.
Light guides made from a high refractive index material have been successfully employed to create a line of light from a point source. For example, one approach discloses an optical element that uses a total-internal reflection light guide to create a line of light from one or two light emitting diode point sources by internally reflecting the light along an axis, wherein beams of light escape the light pipe along the axis of the pipe. This form of lighting apparatus is designed such that the light guide is to be hidden inside a wall or panel. In addition, the length of the light line created is limited by the constraints on the length of the mold used to create the light guides. Other approaches also use total internal reflection to create a line of light from a point source. While these approaches achieve a sufficiently thin line of light, the length of the line is effectively limited and the light guides cannot be easily configured end-to-end to create a longer continuous line of light. Furthermore, these approaches use a very limited number of light sources, which in turn restricts the luminance and perceived visual brightness of the resulting line. The approaches use light guides to direct a point source of light into a line of light, so each approach is limited on luminance. As such, a line of light with high luminance and sufficient length cannot be achieved. An additional drawback is the fact that only a single pattern is achievable with this type of display. Furthermore, for ultraviolet light emitting devices, long light guiding layers are expensive.